1. The Field of the Invention
The present invention relates to structures used for mounting a liquid level sensor in a liquid containing vessel such as a waste tank or water tank like those used on aircraft.
2. The Prior Art
In many types of liquid containers and tanks, including water tanks and waste tanks used on aircraft, it is important to periodically monitor the liquid level in the tank, for example, to prevent overflow, to recognize when refilling is necessary, and so forth. This is done typically by mounting some type of liquid level sensor, such as one using sonar techniques or other electronic sensors, at an appropriate location to enable the sensor to periodically provide a reading of the liquid level in the tank.
One previously used approach to mounting such level sensors involves the forming of an opening in the tank wall at the appropriate location, inserting the sensor into the opening with a flange provided on the sensor preventing the sensor from dropping into the tank, and then securing the sensor in place in the opening with studs or bolts inserted through bores in the flange. Another approach is described in U.S. Pat. No. 5,065,392 to Lukez. The Lukez reference provides an extension which is bonded to the tank wall. A band clamp is then used to secure the sensor to the extension. The band clamp can be readily applied and removed allowing the sensor to be easily replaced.
It is often the case that the vessels contain pressures which are higher or lower than the surrounding ambient pressure. In the case of these described approaches, and other known approaches, if a component fails the sensor can either be sucked into the vessel (when the vessel contains a pressure which is lower than the ambient pressure) or blown out of the vessel (when the vessel contains a pressure which is higher than the ambient pressure). While a leak at a pressure sensor mounting can impair the intended function of a vessel, a catastrophic failure such as a level sensor being blown out of, or sucked into, the vessel can be extremely dangerous, particularly in an aircraft. Thus, it would be an advance in the art to provide an improved level sensor mounting structure for use in vessels.